Heat sink



FIG. 1 is a perspective view of a heat sink, in accordance with the present invention, the enlarged detail is shown for ease of illustration;

FIG. 2 is a front elevational view thereof, the enlarged detail is shown for ease of illustration;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a top plan view thereof, the enlarged detail is shown for ease of illustration; and,

FIG. 7 is a bottom plane view thereof. 

The ornamental design for a heat sink, as shown and described. 